I've found various resources on the internet that seem to talk about similar problems (for example this question and this forum post, but they seem to be out-of-date (ie. not using ArcGIS 10.1) or not asking quite the same question.

Of course, importing osgeo from a normal non-Arc Python window works fine, and I have compared sys.path and os.environ['PATH'] between the scripts and updated them so that they are the same, and it doesn't seem to fix the problem.

I have heard stories of people getting GDAL to work in the ArcGIS python interface before. A few questions: Which method did you use to install GDAL and are you sure you have the correct windows bindings installed and correctly setup? And have you installed the python bindings to the ArcGIS python install?
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LoxodromeAug 14 '12 at 12:03

It looks like you have another version (2.7) of Python installed in addition to the version (2.6) installed by ArcGIS 10. Did you install GDAL for 2.6 as well or are you trying to point it to the version installed for 2.7? Is your 2.7 install a 64-bit installation?
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JasonAug 14 '12 at 13:37

@Robintw there are numerous ways to install GDAL for python. Perhaps you could link me to the executable you used and how you set it up?
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LoxodromeAug 14 '12 at 19:33

2

I've just managed to solve the question - I managed to miss reading the bit above where @Jason asked if I was using a 64-bit installation of Python 2.7. The answer is that my main Python 2.7 install is 64-bit, but Arc's install is 32-bit, so I needed to install a 32-bit version of GDAL, and now it works fine. Thanks everyone - I'll add my final solution as an answer.
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robintwAug 15 '12 at 14:18